A sum of subharmonic and superharmonic function that is subharmonic












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Suppose $u$ and $v$ are subharmonic on a bounded domain $G$ of $mathbb{R}^{n}$ with $ngeq2$, and $w=u-v.$ If $w$ is also subharmonic and defined everywhere on $G$ (we exclude the case $u$ or $v$ is harmonic), can we say that $u$ and $v$ differ by a constant?










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    $begingroup$


    Suppose $u$ and $v$ are subharmonic on a bounded domain $G$ of $mathbb{R}^{n}$ with $ngeq2$, and $w=u-v.$ If $w$ is also subharmonic and defined everywhere on $G$ (we exclude the case $u$ or $v$ is harmonic), can we say that $u$ and $v$ differ by a constant?










    share|cite|improve this question











    $endgroup$















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      1





      $begingroup$


      Suppose $u$ and $v$ are subharmonic on a bounded domain $G$ of $mathbb{R}^{n}$ with $ngeq2$, and $w=u-v.$ If $w$ is also subharmonic and defined everywhere on $G$ (we exclude the case $u$ or $v$ is harmonic), can we say that $u$ and $v$ differ by a constant?










      share|cite|improve this question











      $endgroup$




      Suppose $u$ and $v$ are subharmonic on a bounded domain $G$ of $mathbb{R}^{n}$ with $ngeq2$, and $w=u-v.$ If $w$ is also subharmonic and defined everywhere on $G$ (we exclude the case $u$ or $v$ is harmonic), can we say that $u$ and $v$ differ by a constant?







      real-analysis complex-analysis probability-theory potential-theory






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      edited Dec 25 '18 at 6:14







      M. Rahmat

















      asked Dec 25 '18 at 3:17









      M. RahmatM. Rahmat

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          $begingroup$

          I don't know if I have misunderstood the question but if $v,w$ are (finite) subharmonic and $u=v+w$ then the hypothesis is satisfied, right?






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          • $begingroup$
            Thanks for noticing it. You are right! I edited and excluded this case.
            $endgroup$
            – M. Rahmat
            Dec 25 '18 at 6:15






          • 1




            $begingroup$
            @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
            $endgroup$
            – Kavi Rama Murthy
            Dec 25 '18 at 6:19














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          1 Answer
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          0












          $begingroup$

          I don't know if I have misunderstood the question but if $v,w$ are (finite) subharmonic and $u=v+w$ then the hypothesis is satisfied, right?






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks for noticing it. You are right! I edited and excluded this case.
            $endgroup$
            – M. Rahmat
            Dec 25 '18 at 6:15






          • 1




            $begingroup$
            @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
            $endgroup$
            – Kavi Rama Murthy
            Dec 25 '18 at 6:19


















          0












          $begingroup$

          I don't know if I have misunderstood the question but if $v,w$ are (finite) subharmonic and $u=v+w$ then the hypothesis is satisfied, right?






          share|cite|improve this answer











          $endgroup$













          • $begingroup$
            Thanks for noticing it. You are right! I edited and excluded this case.
            $endgroup$
            – M. Rahmat
            Dec 25 '18 at 6:15






          • 1




            $begingroup$
            @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
            $endgroup$
            – Kavi Rama Murthy
            Dec 25 '18 at 6:19
















          0












          0








          0





          $begingroup$

          I don't know if I have misunderstood the question but if $v,w$ are (finite) subharmonic and $u=v+w$ then the hypothesis is satisfied, right?






          share|cite|improve this answer











          $endgroup$



          I don't know if I have misunderstood the question but if $v,w$ are (finite) subharmonic and $u=v+w$ then the hypothesis is satisfied, right?







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Dec 25 '18 at 6:18

























          answered Dec 25 '18 at 5:33









          Kavi Rama MurthyKavi Rama Murthy

          77.9k53471




          77.9k53471












          • $begingroup$
            Thanks for noticing it. You are right! I edited and excluded this case.
            $endgroup$
            – M. Rahmat
            Dec 25 '18 at 6:15






          • 1




            $begingroup$
            @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
            $endgroup$
            – Kavi Rama Murthy
            Dec 25 '18 at 6:19




















          • $begingroup$
            Thanks for noticing it. You are right! I edited and excluded this case.
            $endgroup$
            – M. Rahmat
            Dec 25 '18 at 6:15






          • 1




            $begingroup$
            @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
            $endgroup$
            – Kavi Rama Murthy
            Dec 25 '18 at 6:19


















          $begingroup$
          Thanks for noticing it. You are right! I edited and excluded this case.
          $endgroup$
          – M. Rahmat
          Dec 25 '18 at 6:15




          $begingroup$
          Thanks for noticing it. You are right! I edited and excluded this case.
          $endgroup$
          – M. Rahmat
          Dec 25 '18 at 6:15




          1




          1




          $begingroup$
          @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
          $endgroup$
          – Kavi Rama Murthy
          Dec 25 '18 at 6:19






          $begingroup$
          @M.Rahmat That doesn't make any difference. Sum of two subharmonic functions is subharmonic . I have changed harmonic to subharmonic in my answer.
          $endgroup$
          – Kavi Rama Murthy
          Dec 25 '18 at 6:19




















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